As the average weight and height of humans continues to increase there is growing debate about relative rider-horse sizes, with riding school horses epitomising the variety of weights of rider that a single horse may be exposed to.

A pilot study led by Dr. Sue Dyson, Head of Clinical Orthopaedics at the Animal Health Trust has highlighted the risks to horses when riders are too heavy, paving the way toward development of guidelines to help all riders assess if they are the right weight for their mount.

The results show that a high rider-to-horse bodyweight ratio can induce temporary lameness and discomfort in the horse. In other words, if the rider is excessively heavy for the horse in question, it can have a negative impact on the performance of the horse.

Researchers says the findings should help in developing suitable guidelines for riders which should enhance equine welfare, rider comfort and enjoyment.

All the horses finished the study moving as well as when they started - any lameness recorded was temporary.


The results do not mean that heavy riders should not ride but suggest that if they do they should ride a horse of appropriate size and fitness, with a saddle that is correctly fitted for both horse and rider.

 “We must remember that this is a pilot study: further work is required to determine if horse fitness, adaptation to heavier weights and more ideal saddle fit will increase the weight an individual horse can carry. This should help us further in our quest to develop guidelines for optimum rider: horse bodyweight ratios.” Dr.Sue Dyson.

Chestnut Horse ridden indoors by a rider being assessed for affects of rider weight on equine performance

The study assessed gait and behavioural responses in six horses ridden by four riders of similar ability but different sizes. The riders were all weighed in their riding kit and were subsequently categorised as being light, moderate, heavy and very heavy.

Each rider rode each horse in its usual tack and performed a set pattern of exercises comprising mainly trot and canter. Gait, horse behaviour, forces under the saddle, the response to palpation of the back, alterations in back dimensions in response to exercise, heart and respiratory rates, salivary cortisol levels and blink rate were assessed for each combination.

rider weight heavy

The riding tests for the heavy and very heavy riders were all abandoned, predominantly because of temporary horse lameness. This was likely to have been induced by bodyweight rather than BMI, given that the heavy and moderate riders had similar BMIs, both being classified as overweight, yet only one of the moderate rider’s tests had to be abandoned. 

A catalogue of behaviours developed by Dr. Dyson specifically to assess behavioural markers which may reflect pain in ridden horses, was applied.

The scores which may reflect pain were significantly higher in the horses when ridden by the heavy and very heavy riders.

The study also raised the issue of rider height and saddle fit. The owner of one of the test horses had a similar bodyweight: horse bodyweight ratio to the heavy rider and was of similar weight, but significantly different in height (157.0 and 185.5 cm, respectively). 

This large difference in height has major potential implications for saddle fit for the rider and consequently the rider’s position and weight distribution. The taller rider sat on the back of the cantle, overloading the back of the saddle and making it more difficult to ride in balance, with the heel being in front of a vertical line between the shoulder and ‘hip’.

Numerous inter-related aspects are involved with the horse and rider combination including the age of the horse, its fitness and muscle development, the length of its back and the presence or absence of lameness. The rider’s skill, fitness, balance and coordination are important factors, as is the fit of the saddle to both the horse and rider. The type, speed and duration of work and the terrain over which the horse is ridden must also be considered.

Roly Owers, Chief Executive of World Horse Welfare, said: “These pilot results are certainly not surprising but are very significant in adding vital evidence to inform an appropriate rider: horse weight ratio. It is common sense that rider weight impacts equine welfare however many might not fully understand or recognise this. What is desperately needed is basic guidance to help riders identify a horse or pony that is right for them and this research is a vital step in that direction.”
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Could you volunteer your horse to help the Animal HealthTrust in their latest ground-breaking study, which aims to help develop guidelines for appropriate rider weight for horses?

The ATH are looking for owners to volunteer their horses to help in their latest ground-breaking study, which aims to help develop guidelines for appropriate rider weight for horses.

"There is an apparent growing problem of riders who are oversized for their horses. It has become a hot topic within the industry and has thankfully drawn attention to the welfare risk to horses, which the AHT seeks to help resolve."

Currently there is a complete lack of reliable scientific research on which to base guidelines for appropriate rider size. However, excessive rider size has clear welfare implications for horses and ponies in all types of work.

"Riders who are too heavy for their horse or pony can cause chronic back pain and lameness, as well as giving the horse a negative association to being ridden as they pre-empt pain. There is therefore an urgent need to start to provide some evidence-based guidelines to the equine industry as to what constitutes excessive rider size, under different circumstances."

During the study horses will be stabled at World Horse Welfare’s Snetterton centre, under the professional care of the AHT team.

Horses put forward for the study will need to be 450-550 kg bodyweight (Approx. 15 – 16hh). They should be in regular work and capable of working two 30 minute sessions in a day, working on the bit in walk, trot and canter.

They will need to be available for 3 – 8 September  and will be stabled on site throughout the study. Any costs involved in travelling to World Horse Welfare, Snetterton will be reimbursed.The horses must also be vaccinated against influenza and tetanus.

The aim of this study is to investigate whether there are any short term measurable differences when horses are ridden.

Owners of the horses taking part will have access to free advice from experts in their field, including vets, saddle fitters, nutritionists and professional riders. The horses will be given a free saddle-fit assessment and any adjustments will also be carried out free of charge.

If you horse is able to take part, they would be helping to take the weight off many other horses’ shoulders, for which they and the AHT would be very grateful.

For more information email: This email address is being protected from spambots. You need JavaScript enabled to view it. or call 01638 751908


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